The invention relates to a device for refracting beams of light, in particular laser beams. Such a device can, for example, be used to accurately direct a laser beam on to a workpiece which is to be processed, to generate graphics, or to inscribe objects by means of laser.
Document DE 41 02 936 A1 discloses a facility used to process materials by means of a polarization-modulated laser beam. The facility comprises a laser, a phase modulator, two reflectors rotating around different axes and a focusing lens. By appropriately adjusting the two rotating reflectors, the laser beam can be focused on any point of a surface of a given size by means of the focusing lens. Materials can thereby be processed as required by means of a laser beam.
Document DE 39 39 866 A1 discloses a device for inscribing the surface of a cylindrical shell by means of laser engraving. This device allows a cylindrical shell surface to be inscribed without having to move the workpiece in relation to the laser beam. For this purpose, a rotation-symmetrical ring reflector is provided, and the symmetry axis of this ring reflector coincides with the symmetry axis of the inscription surface which lies on a cylindrical shell. The rotation-symmetrical ring reflector has a curved reflective surface. With the assistance of a refraction unit comprising two reflectors moving on perpendicular axes, a laser beam emitted from a laser beam source is directed from the reflective surface to the inscription surface.
DE 39 15 254 A1 discloses a process and a device for generating an optical marking on the floor in public areas. A concentrated beam of light (e.g. a laser beam), cyclically traversing a given path, is thereby projected onto a floor covering. The light refraction device, which moves the beam of light along the given path, is controlled at such a high frequency that the marking generated on the floor covering appears stationary.
A common factor of the above refraction systems and numerous other similar devices is that the focus of a laser beam is to be directed precisely and/or at a high speed along a specific path. This means that the associated refraction components (reflectors and the like) need to be precisely and quickly adjusted. The refraction components are thereby generally adjusted by means of rotation around a given axis.
In order to manufacture refraction devices of the afore-mentioned nature, a drive is necessary which allows very rapid and very accurate adjustment of the position (particularly of the angles of rotation) of a refraction component. Such a drive constitutes a considerable cost factor.
It is an object of the invention to create a device for refracting beams of light of the afore-mentioned nature, whereby the refraction components can be adjusted very accurately, rapidly and as cost-effectively as possible.
A device for processing materials and/or generating signs by means of laser beams comprises first and second refraction components rotating around different axes for the purpose of refracting the laser beams. The refractor components are positioned behind one another in the path of the laser beams and each have an activation connection with a drive unit, by means of which rotate around their respective rotation axis. Drive units of the refraction components are respectively formed from the drive motor and the actuator of a read/write head of a magnetic data storage component with a rotating data storage medium in the form of a disk, and whereby the rotation axes of the refraction components are formed from actuator spindles.
Data storage components of this nature are manufactured in huge quantities. This applies in particular to floppy disk drives and hard disk drives of data processing units which are of particular interest in the present case. Each of these drives has a read/write head which can be moved over the rotating floppy disk or hard disk by means of an appropriate drive. Great precision and great speeds are a particularly important property of these drives, in order to facilitate high storage capacity and short access times.
The three afore-mentioned essential properties of read/write head drives (namely low cost as a result of volume production, great precision and high speeds) are used according to the invention to create an accurate, rapid and cost-effective drive for a refraction system.
Document U.S. Pat. No. 5,319,509 does indeed disclose the positioning of a reflector on the actuator of a data storage component, in order to reflect a laser beam. However, the reflected laser beam is passed on directly to a detector positioned in the data storage component, where its reflection angle is evaluated for the purpose of controlling the movement of the actuator. This document makes no reference to the reflected laser beam being directed to another refraction reflector which is also coupled to an actuator in such a way as to create a device for material processing and/or generating graphics.
Furthermore, WO 95/02243 and U.S. Pat. No. 5,153,870 disclose optical data storage components, whereby a laser beam is reflected by a reflector positioned on the actuator of the respective data storage component and then passed on to the read/write head of the actuator. Once again, however, the laser beam remains within the data storage component.
According to an embodiment of the invention, the drive unit for the refraction component encompasses the drive motor of the read/write head of a data storage component with an exchangeable data storage medium (floppy disk, exchangeable hard disk). The advantage of this embodiment of the invention is that because the data storage medium is exchangeable, the respective drive is not hermetically sealed from the outside world and is therefore generally very robust.
On the other hand, it is the read/write heads of data storage components with fixed data storage media (hard disks) that are characterized by particularly high speed and accuracy. For refraction systems upon which particularly high demands are made, the use of such a drive is advantageous.
In order to drive the refraction component according to the invention, it is possible to use either a stage motor or a continuous drive (linear motor). Stage motors are very robust and they allow absolute adjustment of position and angle. Continuous motors facilitate greater precision and speed during component adjustment. However, absolute adjustment of the position of a component is not generally possible with continuous motors. Reaction coupling, which allows the absolute position to be determined, is necessary. For this purpose, so-called servo-tracks and a servo-head are provided with hard disk drives. These servo-tracks and servo-head are not used for data storage, but instead are used exclusively for determining the absolute position of the read-write heads. Comparable devices for determining the position must also be provided when a continuous drive of a read/write head is used to adjust a refraction component.
According to the invention, not only the drive motor of a magnetic data storage component is used for the drive unit of the refraction component, but use is also made of at least part of the device for converting the driving force of this motor into a movement of the head (e.g. the actuator spindle and an arm which swivels around this spindle). For example, therefore, the drive unit of the refraction component can comprise the motor, the complete actuator and, if appropriate, the drive controller of the magnetic data storage component.
It is particularly simple to couple a rotating refraction component to the drive of a read/write head of a magnetic data storage component if this drive encompasses a rotating actuator. The term actuator is used to describe those drive components of the magnetic data storage component which convert the driving force of the motor into a movement of the head. A rotating actuator has an arm which swivels around a spindle at one end and carries the read/write heads at the other end. Upon connecting a refraction component with such an arm in the region of the actuator spindle, a swivel of the arm results in pure rotation of the refraction component.
In this connection it should be pointed out that the term linear motor is used here to describe continuous motors which can be used with both linear actuators and rotating actuators. In hard disk drives, linear motors are used mainly with rotating actuators, in order to generate an arch movement of the read/write heads.
For the purpose of connecting a refraction component to the arm of an actuator, a rod-like component is particularly suitable, whereby this rod-like component is perpendicular to the arm. It is advantageous if the refraction component itself is a reflector. When using a drive for read/write heads to move a refraction component, the arm can of course also be replaced by another component which carries the refraction component and is positioned appropriately on the actuator spindle.
Particularly when using a continuous drive to move the refraction component, it is advantageous if a sensor component group is provided to determine the angle and/or position of the refraction component. In addition, this sensor component group can be used to determine the speed. One component of the sensor component group can thereby be connected to a component (the arm) moving together with the refraction component, while another component of the sensor component group is connected to a stationary component (the actuator axis). In principle, suitable sensors are all types of sensors which allow the position and/or the angle of a component to be very accurately determined, e.g. optic, magnetic and capacitative sensors. The sensor component group is integrated into a regulating circuit which constantly compares the present position of the refraction component with its guide position and triggers the necessary adjustments in the movement of the refraction component.
The electronic control and regulating unit (the regulating circuit) which controls and regulates the movement of the refraction component can encompass the drive controller of a magnetic data storage component. In this case, therefore, not only electromechanical components (motor and actuator) of a data storage component are used to adjust a refraction component, but use is also made of the control gear (drive controller) of the data storage component. The control unit of the refraction component may in some cases encompass additional processors and data storage components which ensure that the refraction component is controlled as required.
As already explained above, the refraction system according to the invention can be used in any application where laser beams are to be directed accurately and/or quickly to different points. Examples include material processing by means of laser beams, generating graphics by means of laser beams and inscribing with laser beams.